1. Technical Field
The disclosure relates to an optical lens assembly, and more particularly to an image-taking lens assembly used in a mobile electronic device.
2. Related Art
In recent years, with the prosperity of the image-taking function in mobile electronic devices, the demand for compact photographing camera lens increases exponentially. The photo-sensing device, e.g. a sensor, of an ordinary photographing camera is commonly selected from a charge coupled device (CCD) and a complementary metal-oxide semiconductor (CMOS) device. In addition, as the advanced semiconductor manufacturing technology enables the miniaturization of pixel size of sensors with the resolution of a compact optical lens assembly being gradually increased, there is an increasing demand for a compact optical lens assembly with better image quality.
A conventional photographing lens usually consists of four lens elements with an aperture stop placed in front of the lens elements. In U.S. Pat. No. 7,365,920 for example, a first lens element and a second lens element which are made of glass and are spherical are bonded together to form a doublet lens for correcting the chromatism. However, with too many spherical lenses in the photographing lens assembly causing the lack of system freedom, the total optical length of the lens assembly would be difficult to be shortened. Also, bonding the first lens element with the second lens element is complicated which creates problems when manufacturing. Moreover, with the miniaturization and the high standard of the image taking lens, assembling the lens assembly in a limited space would create the unnecessary light reflections in the lens barrel and, therefore, affect the image inside the lens. Accordingly, the inventors recognize that to prevent the unnecessary light going into the image area is necessary to maintain the image quality.